Plasma processing apparatus, plasma processing method, and storage medium

ABSTRACT

Provided is a parallel flat-panel type plasma processing apparatus which includes a recipe storing unit storing a processing recipe for performing a plasma processing, a compensation setting unit setting an accumulation time of the plasma processing or the number of processed substrates after starting using a new second electrode and the compensation value of the set temperature of the second electrode in an input screen, and a storage unit storing the compensated set value. The plasma processing apparatus is further equipped with a program for controlling a temperature adjusting mechanism based on a set temperature after compensation by adding a set temperature of an upper electrode written in the processing recipe to the compensation value stored within the storage unit. As a result, the non-uniformity in the plasma processing between the substrates caused by the change of processing atmosphere is suppressed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority from Japanese PatentApplication No. 2011-080133, filed on Mar. 31, 2011, with the JapanesePatent Office, the disclosure of which is incorporated herein in itsentirety by reference. Also, this application claims the benefit of U.S.Provisional Application No. 61/477,182 filed on Apr. 20, 2011, with theUnited States Patent and Trademark Office, the disclosure of which isincorporated herein in its entirety by reference.

TECHNICAL FIELD

The present disclosure relates to a parallel flat-panel type plasmaprocessing apparatus.

BACKGROUND

A parallel flat-panel type plasma processing apparatus used in asemiconductor fabrication process is configured in such a manner that asubstrate placing table serving as a lower electrode and an upperelectrode are placed opposite to each other within a vacuum chamber, andhigh-frequency power is applied between both the electrodes to convert aprocessing gas into plasma. Since a gas supply unit is generallyconfigured as a gas shower head that ejects processing gas in a showertype, the upper electrode is configured by an electrode plate positionedin a lowest part of the gas shower head.

In this apparatus, the temperature of a substrate is determined by heatdissipation to the placing table, heat absorption from plasma, andradiation heat from the upper electrode, but the temperature of theupper electrode is set to a temperature which is considered to beappropriate with respect to some processes. It is difficult to install atemperature detecting unit in the upper electrode and a neighboringregion thereof because a high-frequency power flows on the upperelectrode and the neighboring region thereof. As a result, for example,a value of power supplied to a heater for heating the upper electrodes,which is placed above the gas shower head, is set to an appropriatevalue in advance.

Meanwhile, as the plasma processing apparatus is actuated, a processingenvironment is changed. As a detailed example, in a plasma etchingapparatus, a reaction product in etching may be adhered to a member.When the reaction product is adhered, several changes occur. Forexample, a change in a surface state of a ring member (a focus ring) foradjusting a state of plasma, which is placed to surround a substrateplacing area in the placing table, a change in diameter of a gas supplyhole of the gas shower head, and a change in state of an inner wallsurface of the vacuum chamber occur, such that a processing result or aprocessing speed is changed. Further, according to a verification testof the present inventors, the upper electrode is exposed to plasma, andas a result, a plate thickness may decrease.

In view of operating the apparatus, maintenance of cleaning the insideof the vacuum chamber by periodically converting cleaning gas intoplasma or replacing members with new ones is performed. However, anatmosphere of the processing environment is changed between a state of aso called initialization moment and a moment of operating the apparatusthereafter, and as a result, a processing state between substrates isnot constant. When the lot of substrates is changed, even between aninitial replacement time of the lot and a time when the number ofprocessed sheets of substrates thereafter increases, the environmentatmosphere is also changed to influence processing uniformity among thesubstrates.

Japanese Patent Application Laid-Open No. 2011-3712 discloses atechnology of adjusting the parameters of a processing recipe bysequentially measuring a processing result of the substrate and feedingback the measurement result, and managing an update of a feed-back valueby using an accumulation time of applying high-frequency power or anelapsed time after initialization of the apparatus. However, thistechnique needs an expensive measurement device and deterioration in athroughput based on a time required to measure the processing result isinevitable.

Japanese Patent Application Laid-Open No. 2011-9342 discloses atechnology of operating a substrate processing apparatus of connecting aplurality of process modules (PMs) that perform plasma processing suchas dry etching to the vicinity of a transfer module that transports asubstrate in vacuum. According to Japanese Patent Application Laid-OpenNo. 2011-3712, when a control job (CJ) which is first activated in anyPM does not have a process job (PJ) which is executable in acorresponding PM, the CJ first belongs to another CJ and execution ofthe PJ which is executable in the corresponding PM is permitted. As aresult, an atmosphere within the corresponding PM is prevented frombeing significantly changed whenever the PJ is executed. However,Japanese Patent Application Laid-Open No. 2011-9342 does not disclose atechnology of reducing the influence of the processing environment whichis changed as the apparatus is actuated.

SUMMARY

An exemplary embodiment of the present disclosure provides a parallelflat-panel type plasma processing apparatus including: a processingchamber provided with a first electrode and a second electrode where aplacing table serves as the first electrode configured to place asubstrate, and a high-frequency power is applied between the first andsecond electrodes to convert a processing gas into plasma therebyperforming a plasma processing for the substrate; a temperatureadjusting mechanism configured to adjust a temperature of the secondelectrode; a temperature setting unit configured to set the temperatureof the second electrode in the plasma processing; a set temperaturecompensating unit configured to compensate the set temperature of thesecond electrode to become lower than an initial temperature with a usedtime elapsed after starting using a new second electrode; and atemperature controlling unit configured to output a control signal forcontrolling the temperature adjusting mechanism based on the settemperature of the second electrode.

The foregoing summary is illustrative only and is not intended to be inany way limiting. In addition to the illustrative aspects, embodiments,and features described above, further aspects, embodiments, and featureswill become apparent by reference to the drawings and the followingdetailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal side view illustrating the configuration of aplasma etching apparatus according to an exemplary embodiment of thepresent disclosure.

FIG. 2 is a block diagram illustrating an electrical configuration ofthe plasma etching apparatus.

FIG. 3 is an explanatory diagram illustrating an example of a processingparameter set as a recipe used when plasma etching apparatus isactuated.

FIG. 4 is a compensation value table for compensating the processingparameter.

FIG. 5 is a flowchart illustrating the flow of an operation of theplasma etching apparatus.

FIG. 6 is an explanatory diagram illustrating a temporal change intemperature set value of a heater installed in the plasma etchingapparatus.

FIG. 7 is an explanatory diagram illustrating a temporal change inetching speed of a photoresist layer by the plasma etching apparatus.

FIG. 8 is an explanatory diagram illustrating an experimental result forverifying the temporal change in etching speed of the photoresist layer.

FIG. 9 is an explanatory diagram illustrating a change in temperature ofan upper electrode when a wafer is processed by using the plasma etchingapparatus.

FIG. 10 is an explanatory diagram illustrating the change in temperatureof the upper electrode when the temperature set value of the heater ischanged.

FIG. 11A, FIG. 11B and FIG. 11C each are an explanatory diagram of abackground art according to a second exemplary embodiment.

FIG. 12 is a plan view of a plasma etching apparatus according to thesecond exemplary embodiment.

FIG. 13 is a block diagram illustrating an electrical configuration of aplasma etching apparatus according to the second exemplary embodiment.

FIG. 14 is a compensation value table for compensating a processingparameter between lots by using the plasma etching apparatus accordingto the second exemplary embodiment.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawing, which form a part hereof. The illustrativeembodiments described in the detailed description, drawing, and claimsare not meant to be limiting. Other embodiments may be utilized, andother changes may be made, without departing from the spirit or scope ofthe subject matter presented here.

The present disclosure has been made in an effort to provide atechnology that can suppress the processing uniformity among substratesfrom being deteriorated due to a change in atmosphere of a processingenvironment by using an apparatus in a parallel flat-panel type(capacitively coupled) plasma processing apparatus.

An exemplary embodiment of the present disclosure provides a parallelflat-panel type plasma processing apparatus including: a processingchamber provided with a first electrode and a second electrode where aplacing table serves as the first electrode configured to place asubstrate, and a high-frequency power is applied between the first andsecond electrodes to convert a processing gas into plasma therebyperforming a plasma processing for the substrate; a temperatureadjusting mechanism configured to adjust a temperature of the secondelectrode; a temperature setting unit configured to set the temperatureof the second electrode in the plasma processing; a set temperaturecompensating unit configured to compensate the set temperature of thesecond electrode to become lower than an initial temperature with a usedtime elapsed after starting using a new second electrode; and atemperature controlling unit configured to output a control signal forcontrolling the temperature adjusting mechanism based on the settemperature of the second electrode.

An example of the expression ‘with a used time of the second electrodeelapsed’ may include, for example, the accumulation time of the plasmaprocessing after starting using a new second electrode or the number ofprocessed substrates.

The set temperature compensating unit includes a storage unit configuredto store compensation data acquired by associating a compensation valueof the set temperature of the second electrode with an accumulation timeof the plasma processing or the number of processed substrates afterstarting using a new second electrode, and is configured to read thecompensation value of the set temperature depending on the accumulationtime of the plasma processing or the number of processed substrates fromthe storage unit to compensate the set temperature set in thetemperature setting unit. The set temperature compensating unit includesan input screen for inputting the compensation value of the settemperature of the second electrode with the accumulation time of theplasma processing or the number of processed substrates after startingusing a second electrode.

Another exemplary embodiment of the present disclosure provides a plasmaprocessing method using a parallel flat-panel type plasma processingapparatus having a processing chamber provided with a first electrodeand a second electrode where a placing table serves as the firstelectrode configured to place a substrate, and a high-frequency power isapplied between the first and second electrodes to convert a processinggas into plasma thereby performing a plasma processing for thesubstrate, the method including: setting the temperature of the secondelectrode in the plasma processing; compensating the set temperature ofthe second electrode set in the setting process to become lower than aninitial temperature with a used time elapsed after starting using a newsecond electrode; and controlling a temperature adjusting mechanism foradjusting the temperature of the second electrode based on the settemperature of the second electrode compensated in the compensatingprocess.

The compensating the set temperature of the second electrode isperformed based on compensation data acquired by associating acompensation value of the set temperature of the second electrode withan accumulation time of the plasma processing or the number of processedsubstrates after starting using a new second electrode.

A non-transitory computer-readable recording medium storing a computerprogram that, when executed, causes a computer to control a parallelflat-panel type plasma processing apparatus having a processing chamberprovided with a first electrode and a second electrode where a placingtable serves as the first electrode configured to place a substrate, anda high-frequency power is applied between the first and secondelectrodes to convert a processing gas into plasma thereby performing aplasma processing for the substrate, thereby performing a plasmaprocessing method, including: setting the temperature of the secondelectrode in the plasma processing; compensating the set temperature ofthe second electrode set in the setting process to become lower than aninitial temperature with a used time elapsed after starting using a newsecond electrode; and controlling a temperature adjusting mechanism foradjusting the temperature of the second electrode based on the settemperature of the second electrode compensated in the compensatingprocess.

According to exemplary embodiments of the present disclosure, in aparallel flat-panel type (capacitively coupled) plasma processingapparatus where a first electrode serving as a placing table of asubstrate and a second electrode opposite thereto are installed, a settemperature of the second electrode is compensated to be low with a usedtime of the second electrode elapsed after starting using a new secondelectrode by considering a phenomenon in which the thickness decreasesdue to the use of the second electrode to increase the temperature ofthe corresponding second electrode. Accordingly, a change in temperatureof the second electrode caused by the use of the second electrode can besuppressed and variation in processing among substrates caused by thetemperature change of the second electrode can be reduced.

First Exemplary Embodiment

FIG. 1 illustrates an exemplary embodiment in which a plasma processingapparatus of the present disclosure is applied to a plasma etchingapparatus. Reference numeral 1 represents an airtight vacuum chamber(processing chamber) made of, for example, aluminum. A placing table 2is installed at the center of the bottom of vacuum chamber 1. Placingtable 2 is configured to have a shape in which the periphery of the topof a cylinder is notched throughout the entirety of a circumferencethereof and a step portion 8 is formed, that is, a shape in which a partother than the periphery protrudes cylindrically on the top. Theprotruded portion forms a placing part 20 where a semiconductor wafer (a‘wafer’) W as a substrate is placed and a focus ring 21 for adjusting astate of plasma is placed in step portion 8 surrounding placing part 20.

An electrostatic chuck 22 formed by placing a chuck electrode (notshown) on an insulating layer is installed on the top of placing part20, and adsorption/releasing of wafer W may be switched bysupplying/stopping power from a DC power supply (not shown). A pluralityof ejection openings (not shown) are formed in electrostatic chuck 22,and heat transfer gas such as He gas that performs heat transfer betweenelectrostatic chuck 22 and wafer W is supplied from the ejectionopenings.

A refrigerant passage 231 is formed in placing table 2, and arefrigerant is configured to circulate through a path of a refrigerantsupply path 232, refrigerant passage 231 and a refrigerant dischargepath 233 in this order. The refrigerant discharged from refrigerantdischarge path 233 is cooled up to a predetermined temperature set valueby a chiller to return from refrigerant supply path 232 to refrigerantpassage 231. As a result, placing table 2 is maintained to apredetermined reference temperature by the refrigerant, and thetemperature of wafer W is determined by a balance between heatabsorption from plasma and heat dissipated to placing table 2 throughthe heat transfer gas.

Placing table 2 also serves a lower electrode (first electrode) of aplasma etching apparatus, and a first high-frequency power supply unit31 for generating plasma and a second high-frequency power supply unit32 for applying bias power for injecting ions in plasma are connected toplacing table 2 through matching circuits 310 and 320, respectively.

An elevation pin (not shown) is installed in placing table 2, and waferW may be transferred between a transportation arm (not shown) which isinstalled outside the corresponding apparatus and the top (electrostaticchuck 21) of placing table 2.

A shower head 4 which is a gas supply unit for supplying processing gasinto vacuum chamber 1 is installed on a ceiling of vacuum chamber 1 tobe opposite to placing part 20 through insulating member 11. A pluralityof ejection openings 41 are formed on the bottom of shower head 4, andpredetermined processing gas is supplied into vacuum chamber 1 from aprocessing gas supplying system 42 installed outside vacuum chamber 1through a gas supply path 43, a buffer chamber 44 and correspondingejection opening 41.

Gas shower head 4 is grounded, and a parallel flat-panel is formedbetween gas shower head 4 and placing table 2 as the lower electrode ina lowest part thereof, such that an upper electrode (second electrode)40 for converting the processing gas into plasma is installed. Sinceupper electrode 40 is exposed to a space where plasma is generated,upper electrode 40 is consumed with a use time elapsed by contactingplasma. Therefore, upper electrode 40 is configured by an electrodeplate which is arbitrarily replaced. Ejection openings 41 are openedtoward the inside of vacuum chamber 1 on the bottom of upper electrode40.

A temperature adjusting mechanism 47 that adjusts the temperature ofupper electrode 40 is installed on the top of shower head 4. Temperatureadjusting mechanism 47 is constituted by a cooler 45 including a coolingpath through which a Peltier element or a cooling medium circulates anda heater 46 as a heating unit configured by a heat emitting resistor,and has a function to adjust upper electrode 40 to a desired temperatureaccording to a process situation or a chamber situation (a situation ofeach apparatus installed in vacuum chamber 1) by a combined action ofboth sides.

A carry-in outlet 13 of wafer W which is openable/closable by a shutter12 is installed on a side wall of vacuum chamber 1. An exhaust port 14is installed on the bottom of vacuum chamber 1, and a vacuum pump 17 isconnected to exhaust port 14 through an exhaust pipe 16 where a pressureadjusting unit 15 such as a valve is installed.

The aforementioned plasma etching apparatus is connected to a controlunit 5 as shown in FIG. 1 and FIG. 2. As shown in a block diagram ofFIG. 2, control unit 5 is configured by a computer including, forexample, a central processing unit (CPU) 51 and a program storing unit52, and is connected with processing gas supplying system 42,high-frequency power supply units 31, 32, or pressure adjusting unit 15.

In program storing unit 52, a program is recorded, in which a step(command) group regarding the operation of the plasma etching apparatus,that is, a control until wafer W is carried into vacuum chamber 1 andvacuum-exhausted, and the processing gas supplied into vacuum chamber 1is converted into plasma to etch wafer W, and thereafter, wafer W iscarried out, is embedded. The program is stored in, for example, amemory medium such as a hard disk, a compact disk, a magnet optical diskand a memory card, and installed in the computer therefrom.

In the plasma etching apparatus having the aforementioned configuration,as described as a background art, a phenomenon in which a processingenvironment is changed as the plasma etching apparatus is actuated maybe seen. In particular, the present inventors recognize that the etchingspeed of a film formed on the surface of wafer W gradually decreaseswith an operation time elapsed.

As a result of investigating a cause that generates the phenomenon, thepresent inventors have found out that, when upper electrode 40 isconsumed by exposing to plasma within vacuum chamber 1, the temperatureof corresponding upper electrode 40 increases, and the increasedtemperature reduces the etching speed of plasma.

It is understood that the consumption of upper electrode 40 causes athermal capacity thereof to deteriorate, and as a result, thetemperature of upper electrode 40 increases even though the temperatureis adjusted by temperature adjusting mechanism 47 by setting thetemperature set value to a constant value. It is estimated that adeposition component moves from upper electrode 40 to wafer W as thetemperature of upper electrode 40 increases, such that a depositionproperty of activated species which contributes to etching increasesthereby decreasing the etching speed.

In order to remedy the phenomenon, the plasma etching apparatusaccording to the present exemplary embodiment has a function to preventthe etching speed from decreasing by suppressing the increase of thetemperature of upper electrode 40 through temperature adjustingmechanism 47 as the use time of upper electrode 40 elapsed. Inparticular, since upper electrode 40 constitutes a part of ahigh-frequency circuit and is a member which is difficult to measure thetemperature by using a simple technique, such as a thermocouple, thetemperature is controlled without measuring the actual temperature.Specifically, the relationship between an adjustment amount oftemperature adjusting mechanism 47, for example, a power feeding amountto heater 46 or a flow of a cooling medium to cooler 45 and thetemperature of upper electrode 40 is determined in advance, andtemperature adjusting mechanism 47 is controlled based on therelationship and the set temperature. Hereinafter, details thereof willbe described.

The plasma processing apparatus of the present exemplary embodimentincludes control unit 5. Control unit 5 includes CPU 51, program storingunit 52 storing a program 53, a compensation value setting unit 54 forsetting a compensation value of a parameter (processing parameter), astorage unit 55 storing a parameter compensation value table 551, arecipe storing unit 56 storing a processing recipe, and a work memory57.

Program 53 includes a program for controlling reading the processingrecipe from recipe storing unit 56 and controlling an apparatus toexecute the content of the recipe and a program for compensating aparameter value recorded in the processing recipe by referring toparameter compensation value table 551, and is the general term for theprograms.

Compensation value setting unit 54 receives an input of a compensationvalue of a parameter by an operator through an input screen 541configured by a touch panel type liquid crystal display. As for theparameter, for example, the temperature of upper electrode 40,high-frequency power, processing pressure and processing time may beused as described below. As shown in FIG. 2 illustrating a configurationexample of input screen 541, a compensation interval to compensate thetemperature and a temperature compensation value of upper electrode 40to be compensated for each of the compensation interval elapsed may beinputted into compensation value setting unit 54 according to thepresent exemplary embodiment. The compensation interval or thetemperature compensation value inputted in compensation value settingunit 54 is stored in a rewritable memory.

The compensation interval and the temperature compensation valueinputted into setting screen 541 may be determined by starting using anew upper electrode 40, and thereafter, determining a relationshipbetween an application time of the high-frequency power to upperelectrode 40 and a change in temperature or etching speed of upperelectrode 40 by a preliminary experiment in advance, as shown in, forexample, an experimental result described below.

Recipe storing unit 56 stores the processing recipe prepared byassociating, with the parameter, a processing sequence executed when thefilm formed on the surface of wafer W to be processed is etched. Forexample, in the plasma etching apparatus according to the presentexemplary embodiment, the processing gas or the processing parametersuch as the pressure is switched to consecutively etch multilayersformed on wafer W, and a step for executing the consecutive etching isstored in the processing recipe.

FIG. 3 schematically illustrates a setting example of the processingparameter set for each recipe, and the temperature or processing time ofupper electrode 40 is used as a setting item of the processingparameter. The processing parameter is set, for example, for each stepcorresponding to each of the multilayers to be etched within one recipe,and as a result, different types of layers may be consecutively etched.

Parameter compensation value table 551 is prepared as a table acquiredby associating a timing of performing compensation with a compensationvalue for compensating a set value disclosed in FIG. 3 in regards to asetting item of which a set value needs to be changed, for example, witha time elapsed, among the processing parameters of the respectiverecipes. FIG. 4 illustrates an example of parameter correction valuetable 551 acquired by associating the compensation value of theparameter with the number of sheets of wafers within a corresponding lotwhen the number of accumulated lots of wafers W processed by the plasmaetching apparatus is an N-th lot from a predetermined start moment. Thecompensation value disclosed in parameter compensation value table 551as shown in FIG. 4 is just a numerical value for ease of description.

Parameter compensation value table 551 is prepared by inputting thecompensation value of the processing parameter of the recipe bydesignating the step or wafer W with respect to the setting item asshown in FIG. 3 by using compensation value setting unit 54. Bycompensating the parameter value as described above, for example, afirst wafer W of a corresponding lot is processed for a time that is 3seconds longer than a process time set in the recipe, and a second waferW is processed for a time that is 2 seconds longer than a set value ofthe same recipe in steps S4 and S5.

A compensation temperature calculated based on the aforementionedcompensation interval or temperature compensation value with respect toupper electrode 40 may be set as the compensation value of thecorresponding processing parameter (the temperature of upper electrode40) in parameter compensation value table 551. In the present exemplaryembodiment, the temperature compensation value of upper electrode 40 isnot set in parameter compensation value table 551 and the temperaturecompensation value is set when the corresponding N-th lot is executed bya structure as described below.

The temperature compensation value of upper electrode 40 set inparameter compensation value table 551 is calculated as follows, forexample. Control unit 5 includes a time counting unit (not shown) thatcounts and accumulates the time for which the high-frequency power isapplied from first high-frequency power supply unit 31 for generatingplasma, by using a moment at which the use of a new product as upperelectrode 40 starts as a time count startpoint. Control unit 5 has afunction to add the compensation interval and compare the accumulationvalue (an accumulation time of plasma processing) of the applicationtime of the high-frequency power time counted in the time counting unitwith the addition value. And, whenever the accumulation value of theapplication time is more than the addition value of the compensationinterval, the compensation interval is added. For example, when thecompensation interval of the temperature of upper electrode 40 isrepresented by I_(c) sec and the accumulation value of the applicationtime of the high-frequency power is represented by T_(a) sec, controlunit 5 stands by in such a state during a period of nI_(c)>Ta (n=1, 2,3, . . . ) and when T_(a)>nI_(c), ‘n=n+1 is rewritten to repetitivelyperform a subsequent comparison operation.

Control unit 5 has a function to add the temperature compensation valuewhenever Ta>nI_(c) and write the added temperature compensation value inparameter compensation value table 551 as the compensation value of theprocessing parameter regarding the temperature of upper electrode 40.Herein, when the temperature compensation value is −1.5° C. and thecompensation value at n=1 is 0° C., the compensation value of the lotprocessed during a period in which the application time of thehigh-frequency power is 0≦T_(a)<I_(c) is 0° C., and the compensationvalue of the lot processed during a period of I_(c)≦T_(a)<2I_(c) is−1.5° C. Therefore, the compensation values are sequentially added withthe increase of the application time of the high-frequency power.

Control unit 5 has even a function to generate an execution recipe byadding each compensation value of the N-th lot compensation value tablewhich is generated as above to each value of the processing parameter ofthe recipe performed as the lot.

In program 53, a program for controlling temperature adjusting mechanism47 will be described. This program adds the compensation value writtenin parameter compensation value table 551 to the parameter valueincluded in the recipe read from recipe storing unit 56 and writes theparameter value after compensation in, for example, work memory 57. Inregards to the execution of the recipe, the parameter value aftercompensation within work memory 57 is read to control each unit of theapparatus. The set temperature of upper electrode 40 is included as theparameter value, and the program outputs a control signal forcontrolling temperature adjusting mechanism 47 based on the settemperature after compensation by the aforementioned configuration. Inthe temperature control of upper electrode 40, since a temperaturedetection value is not fed back, the compensation value of the settemperature set in compensation value setting unit 54 may be, forexample, a value acquired by converting a compensated power feedingamount of the power feeding amount to heater 46 into the temperature. Arelationship between an adjusted heat quantity in temperature adjustingmechanism 47 and the set temperature is stored in the storage unit (notshown) as data. And, the adjusted heat quantity, for example, the powerfeeding amount to heater 46, the flow of the cooling medium in cooler45, or the power feeding amount when cooler 45 is configured by aPeltier element, is determined based on the data and the settemperature.

Herein, a correspondence between the respective units in the presentexemplary embodiment and the constituent elements of the appended claimsis described. Since the recipe in recipe storing unit 56 sets thetemperature of upper electrode 40, the recipe corresponds to atemperature setting unit. Compensation value setting unit 54 andparameter compensation table 551 correspond to a set temperaturecompensating unit, and the program corresponds to a temperaturecontrolling unit that outputs the control signal for controllingtemperature adjusting mechanism 47 based on the set temperature.

Hereinafter, the operation of the plasma etching apparatus having theaforementioned configuration will be described with reference to aflowchart as shown in FIG. 5. First, in regard to the executed N-th lot,the accumulation value of the application time of the high-frequencypower and the addition value of the compensation interval are comparedwith each other, and a unit temperature compensation value for eachcompensation interval is added to acuire the temperature compensationvalue (step K1).

Continuously, the temperature compensation value of upper electrode 40is written in the compensation value table of the processing parameter(step K2), the temperature setting value of heater 46 is read from therecipe of recipe storing unit 56, the read temperature set value iscompensated by the temperature compensation value of the compensationvalue table, and the compensated temperature set value is written inwork memory 57 as the execution recipe (step K3).

Herein, as shown in FIG. 4, when the temperature of heater 46 iscompensated, common temperature compensation is performed with respectto all wafers W within the same lot to suppress a sudden change in ageneration state of plasma, thereby preventing processing results amongwafers W within the same lot from being significantly different fromeach other.

Compensation based on the compensation value of the compensation valueparameter is performed even with respect to another processing parameterwithin the corresponding recipe to be written in work memory 57 as theexecution recipe.

Meanwhile, a transportation arm (not shown) holding wafer W entersvacuum chamber 1 from an external vacuum transportation chamber, andwafer W is transferred to placing table 2 through an elevation pin (notshown), and adsorption of wafer W is maintained by electrostatic chuck22. Heat transfer gas is supplied to a gap between placing table 2(electrostatic chuck 21) and wafer W.

An anti-reflection layer, an organic layer or a low-dielectric layer islaminated on the surface of wafer W, and pattern masks of a resist layerand a titanitride layer are formed on an uppermost surface.

Thereafter, the execution recipe is read from work memory 57, and powersupply from first and second high-frequency power supply units 31 and32, the supply of the processing gas from processing gas supplyingsystem 42, vacuum exhaustion by vacuum pump 17, or pressure adjustmentby pressure adjusting unit 15 is performed, such that plasma isgenerated in a processing atmosphere between lower electrode (placingtable 2) and upper electrode 40.

Thin-film etching of the surface of wafer W is performed while ions inplasma are injected into wafer W by bias power. Thereafter, based on theprocessing parameter of the execution recipe, the processing gas or asupply amount thereof and the high-frequency power or process pressureare switched, and lower layers are etched in sequence.

In this case, even in regard to an output of heater 46 installed inupper electrode 40, the temperature adjustment is performed bytemperature adjusting mechanism 47 based on the temperature set valueafter compensation read from the execution recipe within work memory 57(step K4). That is, for example, a control for reducing the quantity ofemitted heat of corresponding heater 46 is performed so as to offset thetemperature increase caused by the consumption of upper electrode 40.

Herein, in order to easily understand the exemplary embodiment, if theset temperature of upper electrode 40 is the same in each processrecipe, the temperature set value of heater 46 decreases stepwise asshown by a solid line in FIG. 6, and the actual temperature of upperelectrode 40 is maintained to a temperature within a substantiallyconstant range. As a result, etching speed of various layers formed onthe surface of wafer W varies within a constant range in a sawtoothshape according to a stepwise change in the temperature set value asshown by a solid line in FIG. 7. Herein, FIG. 7 schematicallyillustrates a state of an etching speed when a single layer configuredby photoresist PR is etched. Dotted lines shown in FIG. 6 and FIG. 7indicate the corresponding temperature set value and the etching speedof PR when the temperature set value of heater 46 is not compensated.Therefore, the layer is etched in an appropriate state even when thetemperature set values of upper electrodes 40 are different from eachother among the respective recipes or the respective steps within therecipe. However, a phenomenon in which appropriateness is deficient dueto the temperature increase caused by the consumption of upper electrode40 is suppressed by compensating the temperature set value.

By this configuration, when a lamination layer to be processed, which isformed on the surface of wafer W, is etched, the supply of theprocessing gas or the heat transfer gas stops and wafer W is carried outfrom vacuum chamber 1 in a reverse operation to the carry-in operationby cancelling a vacuum state within vacuum chamber 1 or adsorptivelyholding wafer W (end). Multiple wafers W may be etched by repeating theaforementioned operation with respect to wafer W that is carried intovacuum chamber 1.

According to the plasma etching apparatus of the present exemplaryembodiment, the following effects are provided. As a parallel flat-paneltype (capacitively coupled) plasma etching apparatus where lowerelectrode (first electrode) also serving as placing table 2 of wafer Wand upper electrode (second electrode) 40 opposite thereto areinstalled, a set temperature of upper electrode 40 is compensated tobecome lower than an initial temperature with a used time of upperelectrode 40 elapsed after starting using a new upper electrode 40, byconsidering a phenomenon in which the thickness decreases due to the useof the upper electrode 40 thereby increasing the temperature of thecorresponding upper electrode 40. As a result, the phenomenon in whichthe temperature of upper electrode 40 increases caused by theconsumption of upper electrode 40 is schematically offset, thetemperature change in corresponding upper electrode 40 caused by the useof upper electrode 40 is suppressed, and variations in processing amongwafers W caused by the temperature change of upper electrode 40 may bereduced.

The example of compensating the set temperature of upper electrode 40with the accumulation time of plasma processing after starting using newupper electrode 40 has been described in the aforementioned exemplaryembodiment, but a technique of measuring the elapsed time is not limitedthereto. For example, the set temperature may be compensated with anincrease in the number of processing sheets of wafers W after startingusing new upper electrode 40.

[Evaluation Experiment in First Exemplary Embodiment]

By using the apparatus such as the plasma etching apparatus as shown inFIG. 1, a test operation was performed without compensating thetemperature of upper electrode 40. In the test operation, a test wafer Wwas carried into vacuum chamber 1 at the same interval as an actualoperation and a predetermined test process environment was formed, suchthat only predetermined sheets of test wafers W where the PR layer wasformed on the surface thereof were processed. The etching speed wasacquired with respect to the PR layer on the test wafer by measuring thelayer thickness before and after the test process.

In regard to a condition of the test process, as processing gas,fluorocarbon gas, argon gas, and oxygen gas were used, pressure invacuum chamber 1 was set to 30 [mTorr] (3.99 [Pa]), power supplied fromfirst high-frequency power supply unit 31 for generating plasma andhigh-frequency power supply unit 32 for bias were set to 12.88 MHz, 4500W and 40 Hz and 1200 W, and the process time was set to 600 sec.

The measurement values of an etching speed at each timing were plotted,and a straight line showing a tendency of the change in etching speed ofthe PR layer was extracted based on the plot group to acquire a resultas shown in FIG. 8. In test results acquired by attaching referencenumerals A to D of FIG. 8, vacuum chambers 1 which are tested aredifferent from each other, and test start timings are different fromeach other. An additional running test was performed with respect toeach vacuum chamber 1 until this test was performed, and based on a factthat a history of the running test was different for each vacuum chamber1, it could be seen that a slope or a timing of the straight line isdifferent, but the etching speed tends to decrease with the time elapsedeven in regard to the test result of any one of A to D.

Based on the result, a level of contribution of a temporal change in theetching speed of the PR layer was analyzed together with abrasion offocus ring 21, and as a result, it was proved that the level ofcontribution of the temperature of upper electrode 40 is significantlylarge.

In the same vacuum chamber 1, upper electrode 40 that was used andconsumed in the actual operation is replaced with upper electrode 40 asa new product to process five sheets of wafers W for each upperelectrode 40. A test thermometer was installed at the center of upperelectrode 40 and the temperature was monitored, and as a result, aresult as shown in FIG. 9 could be acquired.

According to the test result as shown in FIG. 9, when plasma etching ofwafer W starts, the temperature of upper electrode 40 increases and whenthe etching ends, the temperature decreases. This regard was common inthe case where upper electrode 40 is the new product (shown by thedotted line in FIG. 9) and the case where upper electrode 40 is the usedproduct (shown by the solid line in FIG. 9).

Meanwhile, it could be seen that any one of a temperature which upperelectrode 40 reaches during the plasma etching and a temperature afterthe plasma etching is the higher in the case where upper electrode 40 isthe used product. From the test result, it is understood that thetemperature increase of corresponding upper electrode 40 caused by theconsumption of upper electrode 40 influences the phenomenon (FIG. 8) inwhich the etching speed decreases with respect the PR layer.

Therefore, the test as shown in FIG. 9 was performed by using upperelectrode 40 as the new product and changing the temperature set valueof heater 46 heating upper electrode 40. As a result, when thetemperature set value of heater 46 was 150° C. (shown in the dottedline) and 180° C. (shown in the solid line), respectively, as shown inFIG. 10, it could be seen that the substantially same temperaturedifference as the temperature set value of heater 46 was generated inthe temperature of upper electrode 40 in the plasma etching.

By the test results as shown in FIG. 8 to FIG. 10, it could be seen thatas the application time of the high-frequency power to upper electrode40 increases, when the temperature set value of heater 46 decreased, thetemperature increase caused by the consumption of upper electrode 40 iscancelled to suppress the decrease in etching speed.

Second Exemplary Embodiment

The second exemplary embodiment of the present disclosure is atechnology that is not limited to compensation of the temperature setvalue (a supplied power value to the heater) of heater 46 but reviewedby considering how to compensate the processing parameter configuringthe recipe of the plasma etching apparatus. First, referring to FIG.11A, FIG. 11B and FIG. 11C, variation in the processing result of thewafer will be schematically described.

By considering a line width after etching in the case where an etchedlayer of wafer W with a resist mask is etched, the line width afteretching may tend to be thicker from CD1 to CD2 as shown in FIG. 11A as aused time (process time) elapsed after cleaning the plasma etchingapparatus at, for example, a time T1.

The plasma etching executed at the time T1 immediately after thecleaning as shown in FIG. 11A will be described in more detail. The linewidth gradually becomes thicker as shown in FIG. 11B with the increasein the number of processing sheets of wafers W even within the same lot,and as a result, the line width tends to be saturated with a thicknessof CD3.

As such, when the change in line width between the lots (FIG. 11A) andthe change in line width among wafers W within the same lot (FIG. 11B)occur depending on the used time of the plasma etching apparatus, thechange in line width after etching at the time when a time T2 elapsedafter the cleaning is shown in FIG. 11C. In this case, the line width atthe time of starting the corresponding lot is CD2 and the line widthgradually becomes thicker, and as a result, the line width is saturatedwith a line of CD2+(CD3−CD1).

Herein, the examples as shown in FIGS. 11A to 11C are schematicallyexpressed in order to easily understand a background art according tothe second exemplary embodiment and are not described according to anactual characteristic. However, it is understood that the processingresult is changed among the lots with the used time of the plasmaetching apparatus elapsed and two types of changes having different timescales in which the processing result is changed among wafers W withineach lot even in other control items such as the etching speed than theline width of the etching.

Therefore, a technology for making the processing result among the lotsand wafers W within the same lot constant (suppressing the variation)will be described by using a system of FIG. 12 as an example. The plasmaprocessing apparatus of FIG. 12 is an example of a multi-chamber typeplasma etching apparatus that extracts wafer W from a FOUP 100 onplacing table 101 and transports and processes wafer W to each of plasmaetching units 111 to 114 connected to corresponding vacuumtransportation chamber 105 through a load lock module 104 and a vacuumtransportation chamber 105 by using a transportation arm 103 installedwithin a loader module 102.

Each of plasma etching units 111 to 114 is configured as the parallelflat-panel type plasma etching unit according to the first exemplaryembodiment as shown in FIG. 1, and may etch wafer W independently.Reference numeral 106 as shown in FIG. 12 is the transportation arminstalled within vacuum transportation chamber 105.

A case in which wafer W for one lot extracted from FOUP 100 is carriedinto two plasma etching units 111 and 112, and plasma-etchedconcurrently in the multi-chamber type plasma etching apparatus havingthe above configuration will be described. For example, 25 slots capableof holding each one of 25 wafers W are formed in FOUP 100, and slotnumbers 1 to 25 are allocated to the slots in sequence from the top.

Since an etching process is performed in parallel in plasma etchingunits 111 and 112, wafers W of odd-numbered slots of Nos. 1, 3, 5, . . .are carried into plasma etching unit 111 and wafers W of even-numberedslots of Nos. 2, 4, 6, . . . are carried into plasma etching unit 112.

FIG. 13 illustrates an electrical configuration of the plasma etchingapparatus performing the processing. In the figure, the same referencenumerals as the reference numerals as shown in FIG. 2 refer to commonconstituent elements to the plasma etching apparatus according to thefirst exemplary embodiment. The plasma etching apparatus according tothe second exemplary embodiment is different from that of the firstexemplary embodiment in that storage unit 55 includes two types ofparameter compensation value tables 551 and 552 of parametercompensation value table 552 for compensating the parameters among aplurality of lots and parameter compensation value table 551 forcompensating the parameters among wafers W within the same lot.

Compensation values for processing parameters for first and secondwafers W within the same lot are stored in parameter compensation valuetable 551 for compensating the parameters within the same lot betweenparameter compensation value tables 551 and 552 like the compensationvalue table as shown in FIG. 4 which is the first exemplary embodiment.However, the second exemplary embodiment is different from the firstexemplary embodiment in that a common compensation value is adoptedamong the lots.

Herein, parameter compensation value table 551 within the lot is set toeach of plasma etching units 111, 112. As a result, first, second,third, . . . compensation values of parameter compensation value table551 of plasma etching unit 111 are used with respect to wafers W of theodd-numbered slots of Nos. 1, 3, 5, . . . of FOUP 100. First, second,third, . . . compensation values of parameter compensation value table551 of plasma etching unit 112 are used with respect to wafers W of theeven-numbered slots of Nos. 2, 4, 6, . . . of FOUP 100.

Herein, when 25 sheets of wafers W are included in one lot, wafers W ofodd-numbered slots are carried into plasma etching unit 112 in a nextlot and wafers W of even-numbered slots are carried into plasma etchingunit 111. In accordance therewith, parameter compensation value table551 of plasma etching unit 112 is used when wafers W of odd-numberedslots are processed in next FOUP 100 and parameter compensation valuetable 551 of plasma etching unit 111 is used when wafers W ofeven-numbered slots are processed.

Meanwhile, in compensation value table 552 among the lots, for example,after cleaning, wafer W that is first processed is set as the first oneand a compensation value for the number of processed sheets of wafers Wof accumulation of the plurality of lots is set, as shown in FIG. 14.For example, in the example as shown in FIG. 14, the compensation valueof each processing parameter is set every the number of sheets of wafersW of accumulation that are carried into each of plasma etching units111, 112, for example, 100 sheets. The compensation value is set foreach of plasma etching units 111, 112 even in regard to compensationvalue table 552 among the corresponding lots.

As such, control unit 5 adds the compensation value of each ofcompensation value table 551 within the lot and compensation value table552 among the lots with respect to the processing parameter of theselected recipe within recipe storing unit 56 based on a set-up ofrecipe compensating program 53 within program storing unit 52.Therefore, the execution recipe is generated for each of plasma etchingunits 111 and 112 to be written in work memory 57.

Each of plasma etching units 111, 112 executes plasma etching based onthe processing parameter read from the execution recipe. The executionis performed by a process program 53 a within program storing unit 52.Variations between wafers W among the lots and within the lots aresuppressed, which are described with reference to FIGS. 11A to 11C, bygenerating a new execution recipe whenever the lot is switched, therebymaintaining the processing result constantly.

Herein, the example of switching the compensation value based on thenumber of sheets of wafers W has been described in parametercompensation value tables 551, 552 as shown in FIG. 4 or 14, but thecompensation value may be switched based on other time references. Forexample, in parameter compensation value table 551 among the lots, thecompensation value may be switched based on the number of accumulatedlots which are processed, and the compensation value may be switchedbased on an accumulation time when plasma processing is performed, suchas the application time of the high-frequency power. The compensationvalue may be switched based on the elapsed time after starting theprocessing or the accumulation value of the application time of thehigh-frequency power even in regard to compensation table 552 within thelot.

The example of performing only the compensation among the lots withrespect to upper electrode 40 has been described in the first exemplaryembodiment, but compensation of changing the compensation value withinthe same lot may be performed by applying the second exemplaryembodiment to the example.

The technology of the second exemplary embodiment may be applied to aserial type plasma etching apparatus as well in which other plasmaetching units 111 to 114 consecutively perform etching so that in themulti-chamber type plasma etching apparatus as shown in FIG. 12, forexample, plasma etching unit 111 performs plasma etching of steps S1 toS3 and performs plasma etching of steps S4 to S6 by transporting wafer Wto plasma etching unit 112.

The compensation method of the processing parameter according to thesecond exemplary embodiment is not limited to various plasma processingapparatuses such as the plasma etching apparatus, a plasma CVD apparatusand a plasma ashing apparatus. The compensation method may be applied toeven an application and development apparatus or a vertical heatprocessing apparatus.

From the foregoing, it will be appreciated that various embodiments ofthe present disclosure have been described herein for purposes ofillustration, and that various modifications may be made withoutdeparting from the scope and spirit of the present disclosure.Accordingly, the various embodiments disclosed herein are not intendedto be limiting, with the true scope and spirit being indicated by thefollowing claims.

What is claimed is:
 1. A parallel flat-panel type plasma processingapparatus comprising: a processing chamber provided with a firstelectrode and a second electrode where a placing table serves as thefirst electrode configured to place a substrate, and a high-frequencypower is applied between the first and second electrodes to convert aprocessing gas into plasma thereby performing a plasma processing forthe substrate; a temperature adjusting mechanism configured to adjust atemperature of the second electrode; a temperature setting unitconfigured to set the temperature of the second electrode in the plasmaprocessing; a set temperature compensating unit configured to compensatethe set temperature of the second electrode to become lower than the settemperature of the second electrode according to a used time elapsedafter starting using a new second electrode; and a temperaturecontrolling unit programmed to output a control signal for controllingthe temperature adjusting mechanism based on the set temperature of thesecond electrode set by the temperature setting unit and the compensatedtemperature of the second electrode compensated by the set temperaturecompensating unit.
 2. The parallel flat-panel type plasma processingapparatus of claim 1, wherein the set temperature compensating unitincludes a storage unit configured to store compensation data acquiredby associating a compensation value of the set temperature of the secondelectrode with an accumulation time of the plasma processing or thenumber of processed substrates after starting using a new secondelectrode, and is configured to read the compensation value of the settemperature depending on the accumulation time of the plasma processingor the number of processed substrates from the storage unit tocompensate the set temperature set in the temperature setting unit. 3.The parallel flat-panel type plasma processing apparatus of claim 1,wherein the set temperature compensating unit includes an input screenfor inputting the compensation value of the set temperature of thesecond electrode with the accumulation time of the plasma processing orthe number of processed substrates after starting using a secondelectrode.
 4. A parallel flat-panel type plasma processing apparatuscomprising: a processing chamber provided with a first electrode and asecond electrode where the first electrode serves as a placing table ofa substrate as well; a gas supply unit configured to supply a processinggas to the processing chamber; a power source configured to supply ahigh-frequency power between the first and second electrodes to convertthe processing gas supplied therein into plasma thereby performing aplasma processing for the substrate where the second electrode is set toa first temperature; a storage unit configured to store a targettemperature which is lower than the first temperature acquired inadvance by associating with an accumulated time of the plasma processingor the number of processed substrates after start using the secondelectrode; and a temperature controller programmed to read the targettemperature from the storage unit while the substrate is being processedwith the plasma processing and adjust the second electrode to the targettemperature while the substrate is being processed with the plasmaprocessing.
 5. The parallel flat-panel type plasma processing apparatusof claim 4, wherein the temperature controller includes an input deviceconfigured to manually input the target temperature of the secondelectrode with the accumulated time of the plasma processing or thenumber of processed substrates after start using the second electrode.